The present invention relates generally to foam products, and more particularly, to aqueous foamed products of improved workability, reduced sag, and those which will operate under an expanded range of temperatures.
Foam sealants of various kinds have been used in the construction industry, and particularly in the do-it-yourself market, for many years. Such foams have traditionally been of the urethane type, although certain modified acrylic foams and the like have been known for these and other uses.
Among the applications for such foams are filling of cracks, holes around pipes, and in other applications where it is desired to seal the hole or crack against outside weather. In addition, it is often desired to use such foams or the like as patches, over which paint or other decoration is possible. However, foam sealants use for these and like purposes have had a number of drawbacks, particularly in view of the nature of urethane or like products.
Most if not all of these sealants are of the type which adhere strongly to the substrate, be it wood, plaster, vinyl window jams or the like. However, as is the case with urethane foams and other like products, the foams have an extremely sticky nature. Inasmuch as they adhere strongly to the substrate to which they are intended to be applied, they also adhere strongly to the fingers of the person applying them, to paddles or trowels used to apply them or attempting to smooth then out, as well as to the dispensing nozzles or the like from which they are dispensed. Such foams are often capable of only one use, or one use within a short interval, say 5 minutes.
Consequently, there has been a need for a foam which would possess some or all of the qualities of a strongly adherent foam for sealing purposes, but one which could be "cleaned up" with water. Such a foam product would be capable of easy application, following which one could clean the instruments used to apply it, such as a trowel or other similar tool. However, attempts to make a foam that would be useful for filling cracks, openings around pipes, gaps in new or remodeled construction and the like have suffered from considerable drawbacks.
Specifically, although these foams are satisfactory to a certain extent, they are generally very soft and lacking considerably in mechanical strength. In many cases, the foam "skin" is not smooth. The skin possesses many so-called "dragons" formed by leaking and expanding of uncured product through cracks in the skin which are created during foam curing. In other words, the foam first forms a skin, but thereafter, it continues to foam on the inside. When this occurs, the internal expansion causes uncured foam to pass through the cracks in the skin. This creates an undesirable effect, as well as one which requires trimming by the operator. The time for such phenomenon to occur can be considerable, also.
With known foams of the water-based or water-dilutable type, the time for internal curing is exceptionally long. This is particularly amazing when the foam is used for filling larger voids. If the foam is cured under adverse conditions, such as under high humidity, low temperature, or both, curing can be delayed or, in the worst case, not occur at all.
Concerning the application of such foams, both comparatively high and comparatively low temperatures cause a typical to sag significantly from its as-applied condition. By way of illustration, temperatures below 40.degree. and above 85.degree. are not ideal, and in fact, may be unsatisfactory. Such a rather narrow temperature range, is also disadvantageous for use of the product.
In other words, if the foam sought to be cured at either too high or too low a temperature, it may sag significantly. Cured foams of the prior art are not dimensionally stable, particularly when exposed to water over a short period of time. After the foam redries upon being wet, it shrinks to a great extent and this is considered very undesirable.
Where open-backed gaps are large, say three-quarters of an inch or more, it is not possible to fill them successfully with known foams which can be cleaned up with water.
Once the prior art foams are installed, if they are exposed to heat at about 120.degree. F. or higher, the properties of the cured foam gradually begin to deteriorate, and after approximately one week at such temperatures, the foam cores yellow and become porous, losing their texture to a greater or less extent.
Accordingly, it is an object of the present invention to provide an improved, latex-based aerosol foam sealant that is able to be cleaned up with water following use.
Another object of the present invention is to provide a foam which is white in color.
Yet another object of the invention is to provide an improved foam for which the dispensing may be started and then stopped again, even after a fairly long interval, without significantly adversely affecting its properties.
Still another object of the invention is to provide a foam of improved mechanical strength, particularly compression resistance (stiffness) and which is free from friability. In other words, such a foam is not only stronger, but tough and resilient in relation to existing foam products that will clean up readily with water.
A further object of the invention is to provide a foam that is capable of water clean-up, and which, when applied, will have a smooth, thick, consistent skin, free from cracks or the like in its surface.
A still further object of the invention is to provide a foam which will cure not only on the surface, but within the interior of a large volume, or in a mass having a small surface-to-volume ratio.
An additional object of the invention is to provide a foam with water clean-up that is able to fill comparatively large voids or gaps, and which will cure internally when used in these applications.
Another object of the invention is to provide a foam that will cure under conditions of higher humidity and at lower temperatures than its existing counterparts in the prior art.
Yet another object of the invention is to provide a foam which has a high temperature range, up to 120.degree. F. or more, during which the product may be applied and under which it may be cured without sagging or undergoing other adverse effects.
Still another object of the invention is to provide a foam sealant, when cured, is dimensionally stable when exposed to water.
A further object of the invention is to provide a foam which will act as a sealant and which may be exposed in the can to temperatures of up to 120.degree. F. for over one month, or perhaps considerably longer, such as one year, without affecting the characteristics of the foam when it is dispensed from an aerosol container.
A still further object of the invention is to provide a foam which is dispensable in a smooth, controllable, and even in a restartable manner.
An additional object of the invention is to provide a toolable foam, that is, one which may be applied with a trowel or putty knife and one which, when installed, may be painted or decorated without undue trouble.
Another object of the invention, in some cases, is to provide a foam which can be dispensed from an aerosol container without using fluorocarbons or other environmentally undesirable propellants.
In accordance with the foregoing objectives, the present invention achieves these objects and advantages and others which are inherent therein by providing latex-based foam, preferably of an acrylic/vinyl acetate, styrene/carboxylated acrylic copolymer, preferably in an amount of from 60 to 140 parts acrylic latex, from about 0 to 150 parts of a modified latex, from about 25 to 150 parts of corn, potato or other starch, and suitable co-surfactants and/or thickener, coalescing agents, tertiary amines, and blowing agents, the latter preferably comprising from about 0% to 50% dialkyl ether and the balance low molecular weight hydrocarbons such as propane and butane/isobutane.
While the invention will be described in connection with certain preferred embodiments, the invention is not intended to be limited to a listing of such ingredients. On the contrary, the invention is intended cover all alternatives, modifications, and equivalent compositions as may be included within the spirit and scope of the invention as defined by the appended claims.
The present invention contemplates a composition intended to be used with an aerosol container, which upon discharge, creates a foam. Such a foam is comparatively very stable. It is capable of curing throughout into a solid mass of very low density, and generally comprises a foam-forming polymer or polymers in latex form, a starch ingredient such as corn starch or potato starch, a surfactant, and optimally a co-surfactant, foam stabilizer and/or thickener, a pH adjusting agent, and a propellant, preferably in the range of 4% to 6% of the total formulation and comprising, for example, dimethyl ether, propane and isobutane.
All parts include water or other diluent and are by weight in grams as the product is furnished. Thus, for example, 60 grams of Rovace 86 would be about 32 grams of solids.